1) Field of the Disclosure
The disclosure relates generally to apparatus assemblies, systems and methods for compression testing of test specimens, and more particularly, to apparatus assemblies, systems and methods for compression testing of large notch compression test panels, such as panels of component parts of air vehicles.
2) Description of Related Art
Mechanical testing of component parts, or of test specimens of component parts, is often performed in the manufacture of air vehicles, such as aircraft, rotorcraft, spacecraft, and other air vehicles. Mechanical testing provides material property data, such as strength, hardness ductility, and other data about the material as tested under various conditions, such as compression, tension, load and temperature. In turn, the mechanical testing provides information relating to the suitability of a material for its intended application. Such information aids in the design of component parts that will perform as expected.
Mechanical testing of component parts of air vehicles may include compression testing. Compression testing determines the behavior of materials, such as composite or metal materials, under compressive load conditions. Compression testing may be conducted by loading a test specimen, such as a test panel or a flat piece of laminate referred to as a “coupon”, between two support plates of a test fixture.
The test fixture is typically installed in a testing machine, for example, a universal testing machine. The testing machine may apply a compression force or load to the test specimen and may compress the test specimen in a lengthwise direction until it fractures or breaks. The testing machine may record the force required to fracture or break the test specimen. Compressive strength of the test specimen material may be measured by plotting applied force or load versus deformation of the test specimen material. As used herein, “compressive strength” means the maximum compressive load or stress the test specimen material is capable of withstanding before fracturing or breaking.
Test fixtures, apparatus assemblies, and methods for compression testing of air vehicle component parts exist. For example, FIG. 1 is an illustration of a front perspective view of an existing test fixture 10 for compression testing, such as in the form of an existing large notch compression (LNC) test fixture 10a. As shown in FIG. 1, the existing test fixture 10 has a first support plate 12a and a second support plate 12b that sandwich a test specimen panel 28 therebetween. The test specimen panel 28 may be in the form of a large notch compression (LNC) panel.
As further shown in FIG. 1, the first support plate 12a and the second support plate 12b of the existing test fixture 10 completely cover the test specimen panel 28 and obstruct any view of the test specimen panel 28. Thus, use of such existing test fixture 10 precludes use with existing optical strain measurement systems that may be used to optically obtain information relating to strain measurements of the test specimen panel 28.
Instead of using existing optical strain measurement systems, the existing test fixture 10 requires the use of a plurality of strain gages 14 (see FIG. 1) to measure the strain of the test specimen panel 28. As shown in FIG. 1, each strain gage 14 may be positioned laterally across the first support plate 12a, and each strain gage 14 may be coupled to hinge attachment elements 16 mounted on a frame portion 18 of the existing test fixture 10.
However, the use of such strain gages 14 (see FIG. 1) may involve extensive installation time and labor, which results in increased flow time. In addition, the use of such strain gages 14 (see FIG. 1) may require precise alignment and calibration operations, as well as connection to a strain gage machine, prior to testing. This may, in turn, result in increased time and expense of testing. Due to the extensive time involved in installing the strain gages 14 (see FIG. 1) on the existing test fixture 10 (see FIG. 1), test specimen panels 28 may only be tested at a test rate of one (1) or two (2) test specimen panels 28 per day.
As further shown in FIG. 1, the existing test fixture 10 has a base portion 22 and a side support portion 24 (one on each side). However, the base portion 22 may be thin and wear out after several compression tests. Shimming may be required to reinforce the base portion 22 and to hold the first support plate 12a, the second support plate 12b, and the test specimen panel 28 in place. For example, shims 20 (see FIG. 1) may be installed on the existing test fixture 10 (see FIG. 1). However, such shimming process may involve extensive installation time and labor prior to testing. This may, in turn, result in increased time and expense of testing.
Thus, existing methods for compression testing of test specimen panels, such as large notch compression panels, may be expensive and may take four (4) to ten (10) weeks or more to complete. Accordingly, there is a need in the art for an improved apparatus, system and method for compression testing of test specimens, such as large notch compression test panels of component parts of air vehicles, that provide advantages over known apparatus assemblies, systems and methods.